1. Field of the Invention
The present invention relates to a radiation conversion device for irradiating a subject with radiation and capturing a radiation image, and to a radiation image capturing system that uses such a radiation conversion device.
2. Description of the Related Art
In the medical field, a radiation image capturing apparatus, in which radiation is applied to a subject, and radiation that has passed through the subject is directed to a radiation detection device for capturing a radiation image of the subject, has been widely used.
In this case, as types of radiation detection devices, there are known a radiation film on which a radiation image is exposed and recorded, and a stimulable phosphor panel in which radiation energy is stored as a radiation image in a stimulable phosphor, and when stimulating light is applied thereto, the radiation image can be read out as stimulated light. In such radiation detection devices, the radiation film in which a radiation image has been recorded is supplied to a developing apparatus where an image developing process is carried out, or the stimulable phosphor panel is supplied to a reading apparatus in which the radiation image is acquired as a visible image by performing a reading process thereon.
In a medical environment such as an operating room or the like, for performing rapid and precise treatments with respect to a patient, it is essential to read out and display the radiation image directly from the radiation detection device. As a radiation detection device capable of responding to such requirements, a radiation detection device has been developed that uses solid state detection elements, which convert radiation directly into electrical signals, or which, after the radiation has been converted into visible light by a scintillator, convert the visible light into electrical signals, which are read out.
In particular, in a transportable type of device, a battery for supplying electrical power to the radiation detection device and to various electronic circuits is accommodated inside of a casing in which the radiation detection device is housed. The transportable type of device is generally called cassette.
As a charging system for charging the battery of the electronic cassette, it has been contemplated to carry out charging wirelessly. The methods disclosed in Japanese Laid-Open Patent Publication No. 2007-289408 and Japanese Laid-Open Patent Publication No. 2002-336227 may be considered as types of wireless power transmission methods.
According to the method of Japanese Laid-Open Patent Publication No. 2007-289408, a wave-receiving antenna that receives microwaves and a direct current conversion unit that converts the microwaves into a direct current are disposed in a diagnostic X-ray image capturing apparatus, and a microwave power source apparatus is provided, which converts electric power supplied from a commercial power source into microwaves and transmits electricity from a transmitting antenna. In addition, transmission and reception by microwaves is carried out between the transmitting antenna and the wave-receiving antenna, in order to carry out charging of a battery of the diagnostic X-ray image capturing apparatus.
According to the method disclosed in Japanese Laid-Open Patent Publication No. 2002-336227, a transportable type of radiation receiving device is connected to a control apparatus for the purpose of performing signal transmission through a wireless communication connecting means. The wireless communication connecting means makes up a radio connection means, and in particular, serves as a means for transmitting Bluetooth or DECT signals.
Further, as other methods for wireless transmission of electrical power, the following are known: “A Non-Contact Electrical Power Transmission Sheet Envisioned for Embedding in Walls or Floors Appears, Developed at Tokyo University,” IEDM Press, Dec. 4, 2006, (published online at http://techon.nikkeibp.co.jp/article/NEWS/20061204/124943/) and “Wireless Technology Developed to Transmit Power Lights Up a 60 W Bulb in Tests,” Nikkei Electronics, Dec. 3, 2007, vol. 966, pp. 117-128. The method disclosed in the article, “A Non-Contact Electrical Power Sheet Envisioned for Embedding in Walls or Floors Appears, Developed at Tokyo University,” concerns a method for transmission of electrical power by electromagnetic inductance from a primary coil, which is embedded in a non-contact power transmitting sheet, whereas the method disclosed in the article, “Wireless Technology Developed to Transmit Power Lights Up a 60 W Bulb in Tests,” concerns a technique for wireless transmission of electrical power using magnetic field resonance between two LC resonators.
However, with either of the methods disclosed in Japanese Laid-Open Patent Publication No. 2007-289408 or Japanese Laid-Open Patent Publication No. 2002-336227, setting of an on-board battery, to a capacity for enabling capturing of an image and data transmission to be carried out at least one time, is not contemplated.
Further, the method disclosed in Japanese Laid-Open Patent Publication No. 2007-289408 represents a technique for transmitting electrical power by electromagnetic waves with respect to a battery for normal use, which is loaded into a diagnostic X-ray image capturing apparatus. However, it is necessary either for the wave-receiving antenna and the transmitting antenna to be arranged in close proximity, or for the transmission energy to be large in magnitude, such that there is a limit on making the apparatus small in scale and lightweight.
The method disclosed in Japanese Laid-Open Patent Publication No. 2002-336227 is a technique for transmission of electrical power by cables with respect to a battery for normal use. There is similarly a limit on making the apparatus small in scale and lightweight, and moreover, there is a problem in that time is consumed for charging the battery.